Gas-blast circuit breaker with means for throttling gas flow during a switching-out operation



Dec. 13, 1966 H. SCHUBERT 3,291,946

GAS-BLAST CIRCUIT BREAKER WITH MEANS FOR THROTTLING GAS FLOW DURING A SWITCHING-OUT OPERATION Filed May 27, 1964 INVENTOR Helmuih Schubert ATTORNEYS United States Patent 3,291,946 GAS-BLAST CIRCUIT BREAKER WITH MEANS FOR THROTTLING GAS FLQW DURING A SWITCHING-OUT OPERATION Helmuth Schubert, Wettingen, Aargau, witzerland, as-

signor to Aktiengesellschaft Brown, Boveri & Cle, Baden, Switzerland, a joint-stock company Filed May 27, 1964, Ser. No. 370,533 Claims priority, application Switzerland, June 28, 1963, 8,057/63 7 Claims. (Cl. 200-148) The present invention relates to electrical circuit breakers of the gas-blast type and which include at least one set of hollow and exhaust valve equipped load-breaking contacts located in a chamber which is essentially constantly under gas pressure, one of the load contacts being stationary and the other movable, and there being also in this chamber an auxiliary contact connected to the stationary main contact by way of a resistor element.

Gas blast circuit breakers are known wherein one of the load-breaking contacts has a nozzle configuration and the other a pin shape, these two contacts being located opposite one another at a fixed distance, and the electrical load connection between these two contacts being established by means of a slidable bridging contact member which is actuated simultaneously with actuation of the exhaust valve associated with the nozzle-shaped contact. The contacts are located in a circuit breaker chamber which is constantly under gas pressure and which is parallel with the load-breaking contacts, contains a shunt resistance connected in series with an auxiliary breaking point. However, such a construction complicates the construction of the circuit breaker chamber and particularly the path of the auxiliary switching point in the necessary drive direction.

A gas-blast circuit breaker is also known in which the arc extinction device utilizes a dual nozzle arrangement and in which a resistance is present which bridges the are partially during the circuit breaking process and which is led to the path of the are by way of an auxiliary electrode. In this arrangement, the circuit breaker chamber is without gas pressure while in the off position which necessitates a very large separation distance between the load breaking contacts and hence, an undesirably long travel of the movable contact member. It has been further suggested for such a circuit breaker construction to block that nozzle in which the arc section parallel to the resistance is quenched, after this are section has been extinguished.

The object of the present invention is to provide an improved construction for a gas-blast circuit breaker which avoids the disadvantages of the prior construction discussed and which results in a surprisingly inexpensive and simple construction. In accordance with the present invention, the paralleling resistance is located inside of the chamber containing the main load-breaking contacts, this resistance element surrounding the stationary main load contact concentrically therewith and also serving as a carrier for the auxiliary contact which is installed opposite the stationary main load contact in the direction of the movable main load contact. The exhaust valve associated with the hollow stationary main load contact is also so constructed as to block the flow of pressurized gas through the hollow stationary main load contact substantially simultaneously with the separation of the movable main load contact from the auxiliary contact. The hollow movable main load contact member also cooperates with an exhaust valve and wherein means are provided for throttling the amount of compressed air passing outwardly from the extinction chamber through the movable contact member as the latter nears its final position during a switching-out operation. For this purpose the movable 3,291,946 Patented Dec. 13, 1966 contact member is constructed in the form of a double jacketed cylinder including an inner jacket through which pressurized gas within the extinction chamber of the circuit breaker passes during the switching-out operation, and an outer jacket slidable in a drive housing. The space between the two jackets in conjunction with a spring therein serves as a drive cylinder during a switching-in operation and a stationary throttling pin cooperative with the inner jacket by entering it serves to throttle the outflow of the pressurized gas as the movable contact member nears its final switched-out position and prior to closure of the exhaust valve in association therewith.

One suitable embodiment of a circuit breaker incorporating the invention will now be described in and is illustrated in the accompanying drawing which is a central longitudinal section through the breaker.

With reference now to the drawing the circuit breaker is provided with a housing 1, the interior of which serves as a chamber in which the circuit is broken between two sets of symmetrically arranged load breaking points.

The set of load-breaking points or contacts associated with the right part of the circuit breaker chamber, which is symmetrical to each side of the center line 0-0, includes the movable, nozzled-shaped main contact member 2 and a stationary, nozzle-shaped main contact member 25. As illustrated, the two contacts are separated :from each other. The circuit breaker chamber includes a second set of such contacts located to the left of the center line cc but these have not been shown in full in order to simplify the drawings. The load current passes through the two sets of load breaking contacts in series when the contacts are closed.

The movable nozzle-shaped contact is constructed in the mode of a double-jacketed cylinder 2, there being a tubular outer jacket 2a which slides in a drive housing 3 and a tubular inner jacket 21) through which pressurized gas is exhausted from the gas pressurized extinction chamber 1 during a switching-out operation, the outflow of gas being throttled during the final movement of the movable contact member 2 by means of a throttling pin 16 which enters the end of the inner jacket 2b. This end of the inner jacket 2b in association with a sealing disc 17 surrounding pin 16 serves to close off gas flow through the inner jacket 2b. Housed between the inner and outer jackets 2b, 2a of the main contact member 2 is a switching-in spring 4. A tulip-shaped contact member 5 which slides in engagement with the inner jacket of contact member 2 serves to transmit the load current from contact member 2 to the drive housing 3. The outer jacket of contact member 2 carries a damping plate 6 against which a spring 7 supports itself. The chamber 1 is also provided with a radially extending sleeve 1a which serves as a cylinder for receiving a slidable tubular valve body 3. The valve body 8 together with a stationary valve plate 9 located within the chamber 1 in line with the sleeve part 1a forms the exhaust valve for, and on the discharge side of, the movable contact member 2. The drive chamber 10 for the valve body 8 located within the sleeve part 1a communicates with a pneumatic control line, not illustrated, via opening 11. Valved body 8 carries a reaction ring 12 slidable axially on its periphery which serves to close off apertures 13 which connect the chambers 10 and 14. A fixed plate 15 located within the chamber housing 1 is provided with oppositely extending pins 16 on which slide the inner jackets 2b of the left and right hand movable load contact members 2, and the end faces of these inner jackets are arranged to effect a sealing contact with sealing rings 17 carried by plate 15 at the base of each pin 16 so as to close off any fiow of gas through nozzle contact 2.

Secured to the end wall of the housing 1 and within the latter is a plate 20 of insulating material to which is fastened one end of a resistance element 21 which is seen to surround concentrically the stationary main contact member 25. Resistance 21 is so constructed at its other end as to serve as a carrier for the auxiliary contact members 22 of which there are several arranged in peripherally spaced relation around the axis of the main load contact members 2, 25. A connection between this left end of resistance element 21 and the auxiliary contacts 22 is indicated at 23. The connection between the right end of resistance element 21 and the stationary nozzleshaped contact member 25 is indicated by the conductor line 24. Extending outwardly from the end wall 1b of housing 1 and surrounding the nozzle-shaped stationary contact member 25 is a hollow insulator 26 to which the right end of contact member 25 is secured in a suitable manner. The exhaust valve for the nozzle-shaped stationary contact member 25 is indicated schematically at 27. An aperture 28 in the wall of housing 1 serves as a fill hole for replenishing the interior of housing 1 with pressurized gas, for example, through a hollow insulator, not illustrated, on which the circuit breaker structure is mounted.

Operation The improved circuit breaker constuction operates in the following manner. As previously explained, the loadbreaking contacts 2, 25 are illustrated in their open or disconnected positions. In order to switch in the contacts, pressurized gas is introduced through opening 11 into drive chamber and thence through ports 13 into chamber 14 thus moving the piston type valve body 8 downward until chamber 14 communicates with ports 18. After overflowing through ports 18, the pressurized gas reaches chamber 19 established between the outer and inner jackets 2a, 2b of contact member 2 to balance the fluid pressure developed forces within chambers 1 and 19 so that now the switching-in spring 4 causes first the movable main contact member 2 in shifting to the right to engage the auxiliary contacts 22 and subsequently the other stationary main contact member 25. During this movement of contact member 2, damper plate 6, taken along by contact member 2 after a certain partial stroke, functions as a brake by compressing the gas within chamber 29, which thus causes the movable main contact 2 to slow down and strike the stationary main contact 25 with only modcrate-speed. The exhaust valve 27 remains closed while the two contacts 2, 25 are being brought together.

For a switching-out operation to effect disengagement between contacts 2, 25 the drive chamber 10 is vented to atmosphere via aperture 11 which causes the valve body 8 to move in the upward direction under the effect of the pressurized gas on its lower surface. The reaction disc 12, which positions itself in front of the ports 13, thereby makes immediate venting of chamber 19 via ports 18 impossible until the lower end of valve body 8 has cleared the latter. In this manner, the pressure of the gas in the interior on the hollow contacts 2, 25 is first reduced, causing exhaust valve 27 to open in the known manner. After valve body 8 has a cleared ports 18, chamber 19 will be vented by these ports so that now the movable main contact 2 will move to the left and separate from contact 25 to thus break the load current being carried by the circuit breaker. The are drawn between contacts 2, 25 is blown upon by the pressurized gas and quenched. As soon as the inner cylinder jacket 2b of contact member 2 begins to slide over pin 16, the cross-section of the escape path for the pressurized gas will be sharply reduced, thus effecting a sharp reduction in gas consumption. Exhaust valve 27 then closes again automatically in the known manner. The closing instant of valve 27 is advantageously so chosen that it coincides approximately with the instant of separation of contact member 2 from auxiliary contact member 22. The arc thereafter burning between contacts 2, 22, whereby resistance element 21 is now inserted in the circuit, is blown upon and then extinguished solely by the choked flow of gas permeating the interior of the main contact member 2. The blowing action of the gas through the interior of contact member 2 finally ceases as soon as the end face of the inner cylinder jacket 2b of contact member 2 strikes the sealing ring 17. During the contact breaking motion, damper plate 6, after a certain partial stroke of main contact member 2, is taken along by the latter. The gas pressure drop thus created in chamber 19 produces a suction damping effect, through which the main contact 2 is temporarily braked in a position favorable for quenching of the are as between contact members 2, 22.

I claim:

1. In a circuit breaker of the gas-blast type the combination comprising a housing defining therein at least one load breaking chamber constantly under gas pressure and containing a pair of hollow main contact members and a stationary auxiliary contact member, one of said main contact members being movable and the other being stationary, an exhaust valve for each of said hollow main contact members controlling flow of pressurized gas through the same during a switching-out operation, a resistance element within said chamber and through which said auxiliary contact member is connected to said stationary main contact member, said resistance element surrounding said stationary main contact concentrically and serving also as a carrier for said auxiliary contact member which is located intermediate said movable and stationary main contact members when in their switched-out position, said movable main contact member being engageable with said auxiliary contact member prior to effecting engagement with said stationary main contact member, said exhaust valve cooperable with said stationary main contact member being closed to cut off flow of pressurized gas therethrough substantially simultaneously with disengagement as between said movable main contact member and said auxiliary contact member during a switching-out operation, and means effecting a throttling of the flow of pressurized gas through said hollow movable contact member during the latter part of a switching-out stroke thereof subsequent to disengagement as between said hollow movable contact member and said stationary auxiliary contact member.

2. A gas-blast circuit breaker as defined in claim 1 wherein said means effecting a throttling of the flow of pressurized gas through said hollow movable contact member during its switching-out stroke is constituted by a throttling pin enterable into the gas discharge end of said movable contact member.

3. A gas-blast circuit breaker as defined in claim 1 wherein said means effecting a throttling of the flow of pressurized gas through said hollow movable contact memher during its switching-out stroke is constituted by a throttling pin enterable into the gas discharge end of said movable contact member, and wherein said exhaust valve correlated to said movable contactmember is constituted by a sealing disc surrounding said throttling pin at the base thereof and which is finally engaged by said gas discharge end of said movable contact member.

4. In a circuit breaker of the gas-blast type the combination comprising a housing defining therein at least one load breaking chamber constantly under gas pressure and containing a pair of hollow main contact members and an auxiliary contact member, one of said main contact members being movable and the other being stationary, an exhaust valve for each of said hollow main contact members controlling flow of pressurized gas through the same during a switching-out operation, a resistance element within said chamber and through which said auxiliary contact member is connected to said stationary main contact member, said resistance element surrounding said stationary main contact concentrically and serving also as a carrier for said auxiliary contact member which is located intermediate said movable and stationary main contact members when in their switched-out position, said movable main contact member being engageable with said auxiliary contact member prior to effecting engagement with said stationary main contact member, said exhaust valve cooperable with said stationary main contact member being closed to cut oil flow of pressurized gas therethrough substantially simultaneously with disengagement as between said movable contact member and said auxiliary contact member during a switching-out operation, said movable main contact member being a doublejacketed cylinder including an inner jacket through which pressurized gas flows during a switching-out operation and an outer jacket slidable in a drive housing therefor, said space between said inner and outer jackets serving as a drive cylinder, control valve means having a switching-in position in which said drive cylinder is placed in communication with a source of pressurized gas and having also a switching-out position in which said drive cylinder is vented to atmosphere, said valve means being shifted pneumatically from its switching-in position to its switching-out position by discharge of pressurized gas through said inner jacket during a switching-out stroke of said movable contact member, and a throtting pin enterableinto the gas discharge end of said inner jacket during the latter part of the switching-out stroke of said movable contact member to throttle the outflowing gas.

5. A gas-blast circuit breaker as defined in claim 4 wherein said exhaust valve correlated to said movable contact member is constituted by a sealing disc surrounding said throttling pin at the base thereof and which is finally engaged by said gas discharge end of said inner jacket.

6. A gas-blast circuit breaker as defined in claim 4 and which further includes a switching-in spring located in v said space between said inner and outer jackets of said movable main contact member for moving it into engagement with said stationary main contact member following movement of said control valve means to its switching-in position.

7. A gas-blast circuit breaker as defined in claim 4 wherein said exhaust valve correlated to said movable contact member is constituted by a sealing disc surrounding the base of said throttling pin and which is finally engaged by said gas discharge end of said inner jacket, and which further includes a switching-in spring located in said space between said inner and outer jackets of said movable main contact member for moving it into engagement which said stationary main contact member following movement of said control valve means to its switching-in position, and a damper plate secured to said outer jacket and disposed in an annular space between said outer jacket and said drive housing for damping a switching-out movement of said movable main contact member.

References Cited by the Examiner UNITED STATES PATENTS 2,972,666 2/1961 Forwald 200148 3,160,727 12/1964 Colclaser et al 200-148 3,206,582 9/1965 Jussila 200-148 ROBERT K. SCHAEFER, Primary Examiner.

KATHLEEN H. CLAFFY, ROBERT S. MACON,

Examiners.

P. E. CRAWFORD, Assistant Examiner. 

1. IN A CIRCUIT BREAKER OF THE GLAS-BLAST TYPE THE COMBINATION COMPRISING A HOUSING DEFINING THEREIN AT LEAST ONE LOAD BREAKING CHAMBER CONSTANTLY UNDER GAS PRESSURE AND CONTAINING A PAIR OF HOLLOW MAIN CONTACT MEMBERS AND A STATIONARY AUXILIARY CONTACT MEMBER, ONE OF SAID MAIN CONTACT MEMBERS BEING MOVABLE AND THE OTHER BEING STATIONARY, AN EXHAUST VALVE FOR EACH OF SAID HOLLOW MAIN CONTACT MEMBERS CONTROLLING FLOW OF PRESSURIZED GAS THROUGH THE SAME DURING A SWITCHING-OUT OPERATION, A RESISTANCE ELEMENT WITHIN SAID CHAMBER AND THROUGH WHICH SAID AUXILIARY CONTACT MEMBER IS CONNECTED TO SAID STATIONARY MAIN CONTACT MEMBER, SAID RESISTANCE ELEMENT SURROUNDING SAID STATIONARY MAIN CONTACT CONCENTRICALLY AND SERVING ALSO AS A CARRIER FOR SAID AUXILIARY CONTACT MEMBER WHICH IS LOCATED INTERMEDIATE SAID MOVABLE AND STATIONARY MAIN CONTACT MEMBERS WHEN IN THEIR SWITCHED-OUT POSITION, SAID MOVABLE MAIN CONTACT MEMBER BEING ENGAGEABLE WITH SAID AUXILIARY CONTACT MEMBER PRIOR TO EFFECTING ENGAGEMENT WITH SAID STATIONARY MAIN CONTACT MEMBER, SAID EXHAUST VALVE COOPERABLE WITH SAID STATIONARY MAIN CONTACT MEMBER BEING CLOSED TO CUT OFF FLOW OF PRESSURIZED GAS THERETHROUGH SUBSTANTIALLY SIMULTANEOUSLY WITH DISENGAGEMENT AS BETWEEN SAID MOVABLE MAIN CONTACT MEMBER AND SAID AUXILIARY CONTACT MEMBER DURING A SWITCHING-OUT OPERATION, AND MEANS EFFECTING A THROTTLING OF THE FLOW OF PRESSURIZED GAS THROUGH SAID HOLLOW MOVABLE CONTACT MEMBER DURING THE LATTER PART OF A SWITCHING-OUT STROKE THEREOF SUBSEQUENT TO DISENGAGEMENT AS BETWEEN SAID HOLLOW MOVABLE CONTACT MEMBER AND SAID STATIONARY AUXILIARY CONTACT MEMBER. 